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Analysis and Treatment of Internal Leakage and External Leakage of Cryogenic Valves

Analysis and Treatment of Internal Leakage and External Leakage of Cryogenic Valves

1. Internal leakage of cryogenic valve:

Analysis: The internal leakage of the low temperature valve is mainly caused by the wear or deformation of the sealing ring. During the trial operation stage of the project, there are still a small amount of impurities such as sand and welding slag in the pipeline, which will cause wear of the valve sealing surface when the valve is opened or closed.

Treatment: After the valve is on-site for pressure test and installation, the residual liquid and impurities in the valve body must be purged. Therefore, the on-site maintenance measures provided by the manufacturer and the matters needing attention in the on-site test must be combined during the construction stage. Inform the site and strictly control the quality to facilitate the production, operation and maintenance of the project in the future.

 2. Leakage of cryogenic valve:

Analysis: The reasons for the leakage of cryogenic valves can be classified into the following four reasons:

1. The quality of the valve itself is not good enough, with blisters or shell cracks;

2. During the installation process, when the valve is connected to the flange used for the pipeline, due to the different materials of the connecting fasteners and gaskets, after entering the medium in the pipeline, in the low temperature environment, various materials shrink differently, resulting in relaxation;

3. The installation method is wrong;

4. Leakage at the valve stem and packing.

 The processing method is as follows:

1. Before the order notice is issued, the drawings and designs provided by the manufacturer should be confirmed and completed in time, and the factory supervisor should communicate in time. The incoming raw materials should be strictly reviewed, and RT, UT, PT should be carried out according to technical requirements. inspection, and form a written report. Provide a detailed production schedule. In the future production process, if there are no special circumstances, the production should be carried out strictly according to the schedule with guaranteed quality and quantity, and strict inspection work should be carried out before leaving the factory.

2. The valve marked with the flow direction should pay attention to the flow direction mark on the valve body. In addition: For the process, it is very important to control the initial pre-cooling time of the valve so that the valve can be fully cooled as a whole. It is necessary to frequently check whether the inner wall of the valve has cracks, deformation and corrosion of the outer surface, especially for low temperature. The valve of the medium is more prone to thermal expansion and contraction. For the valve under harsh conditions such as cavitation, it is necessary to ensure its compressive strength, low temperature and wear resistance.

Post time: Jul-25-2022